Explanation:
Why is this cluster of galaxies so jumbled?
Far from a smooth distribution,
Abell 2744 not only has knots of galaxies, but the
X-ray emitting hot gas (colored red) in the cluster appears distributed differently than the
dark matter.
The dark matter, taking up over 75 percent of the
cluster mass and colored blue in the
above image, was inferred by that needed to create the distortion of background galaxies by gravitational lensing.
The
jumble appears
to result from the
slow motion
collision of at least four smaller galaxy clusters over the past few billion years.
The above
picture combines optical images from the
Hubble Space Telescope and the
Very Large Telescope with X-ray images from the
Chandra X-Ray Observatory.
Abell 2744, dubbed
Pandora's cluster, spans over two million light years and can best be seen with a really large telescope toward the constellation of the
Sculptor.